Prior to the 1999 Columbine High School massacre, police were trained to wait until the SWAT team arrived before aggressively confronting the shooter with overwhelming force. However, that tactic gave the two Columbine shooters nearly an hour to kill 13 people and wound many others. Today, school-based security officers are trained to immediately respond to shootings before waiting for backup.

CBS News confirmed this image of Scot Peterson (from 2015).

Peterson resigned today after being suspended without pay. He was an armed sheriff's deputy at Marjory Stoneman Douglas High School who Sheriff Israel says stayed outside and never went in to confront the shooter. pic.twitter.com/YpsYJLN5jw

Nikolas Cruz, 19, gunned down 17 people at Marjory Stoneman Douglas High School on Feb. 14. At the time, then-Deputy Scot Peterson was assigned to protect the school.

Broward County deputies are trained to confront a live shooter aggressively, Broward County Sheriff Scott Israel told the Miami Herald shortly after news of Peterson’s response surfaced. The only justifiable reason to run in the opposite direction from danger, as Peterson did, is if advancing would be “absolute suicide” or if the location of the shooting is a trap.

Peterson, who resigned his position on Feb. 22 after being placed on unpaid leave, was observed on video standing outside a building on campus for four minutes while the lone gunman shot his victims with an AR-15 assault rifle. While Peterson stood outside, several students and staff took heroic actions to save others.

Peterson claimed on Monday that he heard gunshots that sounded like they were coming from outside the building, adding erroneously that his training directed him to take “a tactical position” (hide) before assessing the situation.

“Let there be no mistake, Mr. Peterson wishes that he could have prevented the untimely passing of the 17 victims on that day, and his heart goes out to the families of the victims in their time of need,” Peterson’s attorney Joseph DiRuzzo said, according to the Associated Press.

Not surprisingly, President Donald Trump, a draft dodger who has no credibility on the issue of bravery, took a shot at Peterson on Monday for failing to act . Trump claimed that he would have rushed into the school building.